ISO/DIS 11642

IULTCS

Secretariat: ISO

Date: 2024-07-29

Leather — Tests for colour fastness — Colour fastness to water

Cuir — Essais de solidité des coloris — Solidité des coloris à l'eau

DIS stage

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Contents

Foreword

1 Scope

2 Normative references

3 Terms and definitions

4 Principle

5 Apparatus and materials

6 Test pieces

7 Procedure

8 Evaluation

9 Precision

10 Test report

(informative) Commercial sources for apparatus and materials

Foreword

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IULTCS, originally formed in 1897, is a world-wide organization of professional leather societies to further the advancement of leather science and technology. IULTCS has three Commissions, which are responsible for establishing international methods for the sampling and testing of leather. ISO recognizes IULTCS as an international standardizing body for the preparation of test methods for leather.

This document was prepared by the European Committee for Standardization (CEN) Technical Committee CEN/TC 289, Leather, in collaboration with the Fastness Tests Commission of the International Union of Leather Technologists and Chemists Societies (IUF Commission, IULTCS), in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).

This third edition cancels and replaces the second edition (ISO 11642:2012), which has been technically revised.

The main changes are as follows:

• Update of normative references, in particular to ISO 2418 and to ISO 7906.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Leather — Tests for colour fastness — Colour fastness to water

This document specifies a method for determining the colour fastness to water of leather of all kinds at all stages of processing.

The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 7906, Leather — Tests for colour fastness — General principles of testing

ISO 105-A02, Textiles — Tests for colour fastness — Part A02: Grey scale for assessing change in colour

ISO 105-A03, Textiles — Tests for colour fastness — Part A03: Grey scale for assessing staining

ISO 105-A04, Textiles — Tests for colour fastness — Part A04: Method for the instrumental assessment of the degree of staining of adjacent fabrics

ISO 105-A05, Textiles — Tests for colour fastness — Part A05: Instrumental assessment of change in colour for determination of grey scale rating

ISO 105-F01, Textiles — Tests for colour fastness — Part F01: Specification for wool adjacent fabric

ISO 105-F02, Textiles — Tests for colour fastness — Part F02: Specification for cotton and viscose adjacent fabrics

ISO 105-F03, Textiles — Tests for colour fastness — Part F03: Specification for polyamide adjacent fabric

ISO 105-F04, Textiles — Tests for colour fastness — Part F04: Specification for polyester adjacent fabric

ISO 105-F05, Textiles — Tests for colour fastness — Part F05: Specification for acrylic adjacent fabric

ISO 105-F06, Textiles — Tests for colour fastness — Part F06: Specification for silk adjacent fabric

ISO 105-F07, Textiles — Tests for colour fastness — Part F07: Specification for secondary acetate adjacent fabric

ISO 105-F10, Textiles — Tests for colour fastness — Part F10: Specification for adjacent fabric: Multifibre

ISO 2418, Leather — Chemical, physical, mechanical and fastness tests — Position and preparation of specimens for testing

ISO 3696:1987, Water for analytical laboratory use — Specification and test methods

No terms and definitions are listed in this document.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

• ISO Online browsing platform: available at https://www.iso.org/obp
• IEC Electropedia: available at https://www.electropedia.org/

A test piece is soaked in demineralized water and a piece of adjacent fabric, also soaked in demineralized water, laid against each side to be tested. The composite test piece is left under pressure for a specified time in a suitable apparatus. The test piece and adjacent fabric are then dried, and the change in colour of the test piece and the staining of the adjacent fabric assessed with the grey scales.

Leathers with a finish may be tested intact or with the finish broken.

The general colour fastness testing principles shall be in accordance with those described in ISO 7906.

Ordinary laboratory apparatus and

5.1 Test apparatus, consisting of a stainless-steel frame, into which a rectangular weight-piece approximately 5 kg in mass and approximately 115 mm × 60 mm in cross-section fits accurately, so that a uniform pressure of 12,5 ± 1,0 kPa can be applied on the composite test piece, placed between rectangular plates of an inert material, e.g. glass or acrylic-resin, of the same length and width as the weight-piece and about 1,5 mm thick.

The test apparatus shall be constructed so that if the weight-piece is removed during the tests, the pressure of 12,5 kPa remains unchanged.

Other devices may be used provided that equivalent results are obtained.

NOTE An example of a suitable apparatus available commercially is given in Annex A.

5.2 Oven, maintained at 37 °C ± 2 °C.

5.3 Adjacent fabrics (see ISO 7906). Either

1. a multifibre adjacent fabric, complying with ISO 105-F10, measuring approximately 100 mm × 40 mm, or
2. single-fibre adjacent fabrics, complying with the relevant specification in ISO 105-F01 to F07.

NOTE Examples of suitable commercial sources are given in Annex A.

5.4 Demineralized water, grade 3 in accordance with ISO 3696:1987.

5.5 Fine-grained adhesive paper, grade P 180.

5.6 Grey scale for assessing staining, in accordance with ISO 105-A03.

5.7 Grey scale for assessing change in colour, in accordance with ISO 105-A02.

5.8 Spectrophotometer or colorimeter for assessing change in colour and staining, complying with ISO 105-A04 and ISO 105-A05.

5.9 A vessel suitable for evacuation, e.g. vacuum-desiccator.

5.10 Vacuum pump, capable of evacuating the desiccator vessel (5.9) to approximately 5 kPa (50 mbar) within 4 min.

6.1 If the piece of leather available for testing is a whole hide or skin, then first take a sample in accordance with ISO 2418.

6.2 If the leather has a finish and is to be tested with the finish broken, prepare the test specimen as follows:

Cut out a piece of leather approximately 120 mm × 50 mm and lay it out, finish-side down, on a sheet of abrasive paper (5.5), measuring approximately 150 mm × 200 mm, held flat on a work surface. Load the upper side of the piece of leather uniformly with a 1 kg weight. Move the piece of leather approximately 100 mm to and fro on the abrasive paper, carrying out 10 to-and-fro cycles.

NOTE With practice, the same roughening effect can be achieved holding the abrasive paper in the hand.

Brush the roughened area thoroughly to remove all dust. From the roughened area of the leather, cut out a test piece measuring approximately 100 mm × 40 mm.

To test leather for upholstery application with a surface coating, larger leather pieces, e.g. approximately 110 mm × 50 mm can be used to avoid staining caused by contact of water with the leather fibres at the edge.

The fact that the finish has been broken shall be mentioned in the test report.

6.3 If the leather has no finish, or if it has a finish but is to be tested with the finish intact, simply cut out a test piece measuring approximately 100 mm × 40 mm.

6.4 For each test piece cut out a piece (or pieces) of adjacent fabric (5.3), enough to cover the leather sample measuring approximately 100 mm × 40 mm. If both sides are to be tested then another piece(s) of adjacent fabric is required.

7.1 Immerse the test piece and adjacent fabric(s) in demineralized water (5.4) in separate containing vessels, using for example bent glass rods to keep them immersed. If testing more than one test piece simultaneously, several pieces of adjacent fabric may be immersed in the same containing vessel, but each test piece shall be immersed in a separate vessel. Place the containing vessels in the vacuum vessel (5.9), produce a vacuum of approximately 5 kPa within 4 min, and hold this vacuum for 2 min. Restore normal pressure. Repeat the procedure a further two times.

In the case of testing leather for upholstery with a surface coating, wet the surface with water but do not immerse the test piece in water.

Lay a piece (or pieces) of adjacent fabric out on a glass or acrylic-resin plate (5.1) and cover it with the test piece, with the side under test facing down. If both sides are to be tested, cover the test piece with a second piece (or pieces) of adjacent fabric. Cover the composite test piece with a second glass or acrylic-resin plate.

7.2 Preheat the loading weight-piece in the oven (5.2) at 37 °C ± 2 °C for at least 1 h. Place the composite test piece, between the two plates, in the test apparatus (5.1) and load it with the weight-piece. In order to allow excess demineralized water to run off, tilt the apparatus about 30° to each side for a few seconds. (When testing several composite test pieces simultaneously, take care to ensure that each is placed centrally between two plates in such a way that the pressure is exerted evenly on it.) Place the loaded apparatus in the oven and leave at 37 °C ± 2 °C for 180 min ± 10 min.

7.3 At the end of the 180 min period, take off the load, remove the composite test piece from the apparatus, fix it together at one corner (by stitching or stapling), and dry it by hanging it in air at room temperature, with the test piece and its adjacent fabric(s) in contact only at the point they are fixed together.

8.1 When the composite test piece is dry, using D65 illumination according to ISO 7906, visually assess the staining of each kind of fibre in the adjacent fabric(s), using the appropriate grey scale (5.6) in accordance with ISO 105-A03. Also assess the change in colour (5.7) of the test piece in accordance with ISO 105-A02.

8.2 Alternatively, provided the staining and colour change is even, the grey scale staining and colour difference can be assessed instrumentally (5.8) in accordance with ISO 105-A05 and ISO 105-A04.

For the visual grey scale evaluations, an inter-person precision of ± 0,5 grey scale units is normal.

The test report shall include the following information:

1. a reference to this document, ISO 11642:—;
2. a description of the type of leather tested and which surface of the leather was tested;
3. whether there was a finish and, if so, whether the finish was broken;
4. the numerical grey scale ratings obtained for the staining of the adjacent fabric(s), giving a separate grey scale rating for each of the different types of fibre;
5. the numerical grey scale rating obtained for the change in colour of the test piece;
6. details of any deviations from the procedure specified.
7. 
   (informative)
   
   Commercial sources for apparatus and materials

Examples of suitable products available commercially are given below. This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of these products.

A.1 A suitable apparatus is:

• the Perspirometer (Hydrotest apparatus) from Karl Schröder KG, Karrillonstrasse 32, D-69469 Weinheim, Germany. Website: www.schroeder-prueftechnik.de
• the AATCC Perspiration Tester from SDL Atlas UK, Shawcross St., Stockport, SK13JW, UK. Website: www.sdlatlas.com
• the Perspirometer from James H. Heal & Co. Ltd, Richmond Works, Halifax, West Yorkshire HX3 6EP, UK. Website: www.james-heal.co.uk
• the Perspirometer from PFI Germany, Test and Research Institute, Marie-Curie-Strasse 19, D-66953 Pirmasens, Germany. Website: www.pfi-germany.de

Any other suitable apparatus may be used, provided it gives the same results.

A.2 Examples of suppliers for the adjacent fabrics conforming to ISO 105 Standards:

• Swissatest Testmaterialien AG, Mövenstrasse 12, CH‑9015 St. Gallen‑Winkeln, Switzerland. Website: www.swissatest.ch
• SDC Enterprises Limited, Pitcliffe Way, Upper Castle Street, Bradford, BD5 7SG, UK. Website: www.sdcenterprises.co.uk
• Testfabrics Inc., PO Box 26, West Pittston, PA 18643 USA. Website: www.testfabrics.com